Sintered powdered copper base bearing



e i 2,831,243" 1C6 Patented Apr. 22, 1958 I Unite oxide particles are preferable from an economic standpoint s 1nce Alundum and corundurn, for example, cost 2 331,243 l o appreciably less than other typical nickel-titanium alloys or titanium-aluminum powders. Of coursefaluminumv SINTERED PUWDERED COPPER'BASE BEARING 5 oxide also does not contain any relatively critical mate- Robei't F. Thomson, Grosse Pointe Woods, Mich, asrials e nickel tiiehiihh- Signorto General Motors Corporation, Detroit, Mica, On smtenng, moreover, the high-melting um acorporationof Delaware orilife particles alloy with the powdered metal mix to l i w 'ch they are added to a negligible extent as compared N0 Drawing. sfiggi g g ggz a h 9 1954 10 with niclsel-containing compounds and tend to remain in e v a substantially the same form in which they are introduced. 91Claims. (Cl. 29- -1825) Maximum wear resistance normally cannot be obtained if the particlesalloy excessively with the base metal of o i thepowderedmix. 1 j i This invention relates'to" sintered, powdered coppe Other objects and advantages will more fully appear base bearings having a highdegree of wear resistanee from, the following detailed description of preferred emwith orwithout subsequent cold or hot working or therbbdimehts 0f Iny imehtiohmaltreatment; More particularly, the invention per- The bearing is formed by initially thoroughly mixing tains tof sintered powdered copper-base bearing parts flheiy pulverized aluminum Oxide with a PP base containing tin and dispersed particles of aluminumoxide. POWdeI containing The till may be alloyed with Pbfehe metal bearings commonly vh ve been emthe copper, although normally it is separately added to pleyed in industry during reeent years, but their use in the mix in powdered form. Other elements, such as zinc, many applications has been limited because of their relnickel, e manganese, aluminum, Sihebh, beryllium, fi l ,lew wear resistance Aee'ordingly, a principal cobalt, iron and phosphorus, may also be included in the object of this invention is to provide a novel sintered hearing meteriaiy M these e1eme11t$11eYma11y' 1I \ay powdered copper base bearing having a high degree of be Wholly Partially y With the PP Zine,

wear resistance due to the presence of aluminum oxide nickel, lead and aluminum y be P e t in appfeeiable particles. A further object of the present invention is to amounts f y be beneficial Particular P p v provide a simple, inexpensive process for forming a sini t Zinc and e Cements 0f the PP base P tered powderedcopper base bearing of such a composi- 1Il g e range as high as 45 ahd wr a y tionhaving close dimensional tolerances. Likewise, p about ehimlhhm m y be e These and other objects are attained in accordance the P i' metal mlXtllIe, 2 i u with my invention by the addition of aluminum oxide Content being P 'e Seine eQ Nlckel particles to copper base metal powder. Small propormay be PTe$eht 1h e y large q ti as herelhattef fl f i id i k l Powders are also f bl more fully explained. Amounts ot sheen and iron, prefcluded in the powdered metal mix and serve to provide eiabiy i the Order of about 1% t0 3% and t0 11%, the material with [greater corrosionbresistance, ability to respeeuvely, a also be iheiuded- T yel' other age harden, wear resistance and strength. The formed elements te above are normally Pieseht h 'e yery bean'ngpart, whensintered, or when sintered and worked Small quantum?- to a controlled degree of porosity, possesses excellent 40 E e y minute amelmt of e ahimihhhl Oxide wear resistance properties due to the presence of the dis- Powder Improves the W resistance 9} t e h a parsed particles-of l i i measurable extent, and the range of this constituent may- The resultant wear-resistant s'intered powdered copper vMy f t h hbh efieetlye amulet a .q y base metal may be advantageously used to form piston cohstlmiihg PP P Fh 15% 'fi of the fihel pin bushings, camshaft bushings, balancer shaft bush- Heb/ever, e Preylde the desired economy it ings, thrust washers, and other bearing parts. Hence the i Strength, I "E P Strength and jshock word "bearing, as used herein, is intended to include sistehee, the aluminum Oxide content p b yl be all such applications in which relatively moving parts are tfieihtelhee between (1.25% n y Welght, h g in engagement and in which high wear resistance and these physwallpropertles Holmany are Present to a SatlsgOOd anti-score,prqpertiesofithemetal are desirable, factory extent when the aluminum oxide constitutes as Sinteredpowdered; copper 'base bearings formed in 210- much as abellt f- POW- lewd metal mix. I When cordance with the present invention possess not only the more than e h i oxide is used, the ,tenslle aforementioned high wear resistance but also desirable Sirehgih and ductility of the i Powdered {QPPer P oil-retaining properties. "Moreover, these hearings, when 5 beefing are appreciebiy i The excessive b compared with similar parts made by normal manufach s ee g which precludes t eiiecilve h ming'inetheds, do not require the expensive machining in many applications, is evidenced by chipping or cracking operations otherwise frequently necessary to provide the Q W test Specimens when, they f being P' preper tolerances tum, einee little 01-410 machining timum properties are usually obtained when the bearing is necessary", scrap or waste 1s reduced to aminimum.

' contains approximately 1% to 5% of the crystalline alu- ,Recently, sintered powdered copper base, bearings mlhhm OXlde P l have been provided withincreased wear resistance by the I have Obtained best results when the PP t inclusion of either nickel-titanium or titanium-aluminum thteS between xabmlt n 97% 0f the totel mix. a particles in the powdered m tal: mix, Th d l However, it will be understood that the terms copper base meta ,f copper base bearing and rcopper base ments are respectively disclosed in co-pending patent'apv I ie i 397 739 fil d ecembel- 11 1953 i the alloy, as used herein, are intended to encompass alloys name of Robert F. Thomson and co-pendingpatent appliend PeWdeTed meiai mixtures in which, pp is the cation S. N. 444,401, filed July 19,1954, in the names of major constituent and preferably constitutes at least 50% Robert F. Thomson and Eric W. Weinman. However, of a Powdered metal mixture or ythe use of aluminum oxideparticlesin the mix, in aci y divided graphite, Preferably 30 meShV'OI finer, cordance with the present invention, aflords certain admay be mixed with the metal powder to increase tool or vantages over the use of nickel-titanium or titaniumdie lite and to improve frictional characteristics of the 'Thehard, crystalline aluminum formed copper base bearing part. Small amounts of l aluminum particle's." y l graphite not in excess of approximately 6.5% are satisfactory, while a graphite content between about 0.3% and 4% is normally preferred. 3 v

Likewise, in order to eliminate'the necessity of Coating e dies with a lubricant during the briquetting operation, a small but effective amount of zinc stearate powder-not in excess of about 2.5% should also be included in the powdered metal mix. In general, I have found that best results are obtained with'a mix having a zinc stearate content between approximately 0.3% and 2%. Other die'lubricants, such as 'stearic acid in powder form, can also be used in place of the zinc stearate. p

The inclusion of proper amounts of tin and nickel in the powdered metal mix further increases the wear resistance' and score resistance of the formed bearing part. Moreover, nickel also contributes corrosion resistance to the bearing and improves its ability to age harden. Tin melts at alow temperature and alloys with copper to form a tin-copper alloy, the latter coating the substantially pure copper particles. During the sinteringoperation, the elevated temperature causes the tin to diffuse through the copper. The melting point of the metal in the areas previously occupied by the tin is thus raised, thereby providing an alloy having a melting point above the sintering temperature. Since the tin brazes the copper particles together to form a bronze, the resultant metal is a better bearing material than if no tin were present and possesses better corrosion resistance. Furthermore, the tin and nickel, if included in the powdered metal mix, serve to strengthen the bearing. I

Although amounts of tin as high as 18% by weight may be used, optimum results are obtained with a preferred tin content between approximately 1% and 13%. The addition of tin in quantities greater than 18% results in the formation of hard and brittle copper-tin compounds, which tend to produce galling. Alternatively, a bronze powder of similar composition may be employed. .The preferred nickel range is between 2% and 15%, although this element maybe substituted for copper in amounts rangingfrom'a small but effective amount up to the point where the copper content is only slightly higher thanthe nickel content. In no instance, therefore, would the added nickel content exceed about 49% in this copper base bearing material. i

In view of the above considerations, I have found that a sintered powdered copper base bearing having excellent wear resistance is one which comprises approximately 1% to by weight of crystalline Al O powder, 0.3% to 4% by weight of carbon, tin not in excess of 13% by weight, and the balance per. The inclusion of nickel in amounts not in excess of 15% increases the corrosion resistance of the bearing and permits it to be more satisfactorily age hardened.

The tin powder may be added in the form of tin dust, while the nickel may be introduced as nickel powder, such as electrolytic nickel powder or nickel produced from nickel. carbonyl by means of the Mond process or other suitable means. Although nickel may also be used in other forms, it is desirable to add it in the form of nickel powder formed from nickelcarbonyl as its commercially available fine particle size permits quicker homogenization. Electrolytic nickel powder, as commercially supplied, is somewhat coarser grained, and its use necessitates a longer period of time at an elevated temperature to sufiiciently homogenize the powder metal Among the aluminum oxides which may be used are fused A1 0 such as alundum, and the impure Al 0 containing minor amounts of iron oxide and known as Turkish emery. Corundum (a form of natural A1 0 and tabular corun'dum (calcined A1 0 likewise can be successfully employed in' accordance with the present invention. Specific examples of these forms of crystalline aluminum oxides include the commercially available com Alundum 60OX, Alundum 320B, co-

l00}-200 and Turkish pounds identified as rundum 300, tabular corundum substantially all powdered cop- 250 to 350 mesh particles are preferred. Crystalline aluminum oxide particles which are What prone to cause scoring.

Commercially pure copper and tin may be used or, as hereinbefore explained, a bronze powder of appropriate composition maybe used in place of the mixture of copper and tin. Hydrogen reduced copper of approximately mesh has provided excellent results, although the particle size of the copper or bronze may vary from -60 to 325 mesh and still produce a satisfactory bearing. Other metal powders in the base m aterial preferably also should have particle sizes within this range.

The sintered powdered copper base bearingmay vbe formed by first briquetting a mixture of the pulverized aluminum oxide, tin, nickel and copper, together with zinc stearate and graphite powder, ifits is desired to add the latter constituents, at an appropriate pressure in too coarse are somea die having a contour which is complementary to the bearing surface tobe formed. Although a briquetting pressure between approximately 20,000 and 120,000 pounds per square :inch has proved to be satisfactory, 40,000 to 60,000 pounds per square optimum pressure range for most applications. Before briquetting, it is important that thepowdered metal constituents be thoroughly mixed in order to provide uniformity of structure and properties to the resultant bearing.

The green briquette is then sintered under suitable conditions of time, temperature and atmosphere into a structure having a controlled degree of porosity. Sintering temperatures between 1 1300 ing times between fifteen and highly satisfactory for these thirty minutes appear to be powdered copper base briquettes. The above sintering times-are not critical, however, and sintering times as short as four minutes and as long as two hours produce satisfactory wear test results. Excellent results have been obtained'by sintering the briqnettev at approximately'1500" F. for twenty minutes under a non-oxidizing furnace atmosphere, 'such as dissociated ammonia, dry mixture of Neutralene gas. I

The dry Drycolene gas normally is composed, of approximately 20% carbon monoxide, 3% hydrogen and 77% nitrogen. The Neutralene atmosphere mentioned above is a closely related gaseous mixture which usually consists of approximately 1.5% carbonmonoxide, 1.5% hydrogen and 97% nitrogen. It has proved advantageous to use a mixture of lOO parts of Neutralene and one part of natural gas. Of course, other furnace atmospheres, such ashydrogen, mixtures of nitrogen and hydrogen or methane, etc., can be used, but Drycolene and Neutralene are readily available and each provides a highly effective protective atmosphere.

if an appreciable amount of, nickel has been separately includedin the powder metal mix, heat treatment subsequent to sintering is'beneficial. Thus a solution treatment for one to eight hours in a non-oxidizing atmosphere Drycolene gas, or a gaseous and .a small amount of natural at a temperature between approximately 600 F. and

1400 F. may be usedfto provide greater hardness and homogeneity. A two-step process is preferably employed,

room temperature following the solution step.

inch appears to be-the F. and 1950 F. and sinter-:

to be tested iron wheel having a It will be understood that a sintered powdered copper base bearing containing dispersed particles of aluminum oxide in accordance with this invention may be manufactured under the usual porous metal techniques as disclosed in a number'of patents, such as Patents Nos. 1,738,163, 2,097,671, 2,075,444, etc. Also, instead of briquetting the metal powder as hereinbefore explained, it may be molded to shape prior to sintering as suggested in Koehring Patent No. 2,198,702.

Likewise, the powdered metal mix may be merely spread on or otherwise placed in contact with a supporting surface and subsequently sintered. This supporting surface may be a non-porous metal backing strip, such as a steel strip, and the powdered metal may be bonded to the back on sintering. When this latter procedure is used, it may be desirable to first electro-deposit a suitable metal plate on the surface of the back to improve the strength of the bond. This type of process is disclosed in Koehring Patents Nos. 2,187,086 and 2,198,253. After sintering, the composite of spongy copper base alloy on the back may be rolled to increase the density of the powdered metal bearing and then resintered or annealed. Additional rolling and annealing treatments can be employed to further increase the density of the bearing. In this manner a highly wear-resistant sintered bronze bearing layer, for example, can be formed on a steel back.

All of the above modifications are understood to be within the scope of the present invention, which broadly comprehends the provision of a sintered powdered copper base bearing containing tin and/or nickel and dispersed particles of aluminum oxide.

Wear tests were conductedto compare sintered copper base metal samples formed in accordance with my invention with sintered copper base samples containing no aluminum oxide particles. These samples were prepared as tensile bars briquetted at a pressure of 60,000 pounds per square inch. They were then sintered for 25 minutes in a dissociated ammonia atmosphere at a temperature of 1575 F. and subsequently cooled in this atmosphere. None of the samples was forged. Each specimen was machined to prepare a inch by 1% inch rubbing surface. The specimens were next successively locked in a fixture of the wear test machine and placed in contact with a rotating smooth-surfaced cast face width of one inch. Increased wear resistance was measured by decreased weight loss in grams and in decreased volume loss in cubic inches.

A wear test using this apparatus was conducted in which the specimen load was increased to 512 pounds and retained at this figure for a total test period of five hours. At the end of this time the sintered copper base test specimens which did not contain aluminum oxide particles showed an average weight loss of 0.341 gram, while copper base'samples containing crystalline A1 0 particles lost an average of only 0.0426 gram. Similarly, while the former specimens 269 cubic inches, the test specimens formed m accordance with the'pi-esent invention changed on the average only approximately 11x10" cubic inches. The results of these tests, which show the relatively low weight and low volume loss of my new sintered powdered copper base bearing material under severe wear test conditions, illustrate its high wear resistance.

While the present invention has been described by means of certain specific examples, it is to be understood that the scope of the invention is not to be limited thereby except as defined in the following claims.

1 claim: s

1. A highly wear-resistant sintered powdered metal comprising approximately 0.25% to 15% A1 0; particles,

2% to 15% nickel, and the balance substantially all a underwent a volumeloss averaging metal selected from the class consisting of copper and copper base alloys.

2. A wear and corrosion-resistant metal bearing consisting essentiall' 0.25 to 7% aluminum oxide, 2% to 15% nickel powder, 0.3% to 6.5% carbon, and the balance substantially all powdered bronze.

3. A highly wear-resistant sintered powdered metal bearing consisting essentially of about 0.25% to 7.5% aluminum oxide in the form of dispersed finely divided particles, tin not in excess of 18%, 2% to 15%, and t .e balance substantially all copper.

4. A sintered powdered metal bearing characterized by high wear resistance, said bearing being formed from a powdered metal mixture consisting essentially of 1% to 5% crystalline Al O particles, carbon not in excess of 6.5%, 1% to 13% tin, 2% to 15% nickel, and the balance substantially all powdered copper.

5. A sintered powdered metal bearing characterized by oil-retaining properties and high wear resistance, said bearing formed from a mixture consisting essentially of about 1% to 13% tin powder, 2% to 15 nickel powder, 1% to 5% A1 0 powder, 0.3% to 4% carbon, 0.3% to 2% die lubricant, and 70% to 97% copper powder.

6. A sintered powdered metal bearing characterized by high wear resistance, said bearing being formed from a powdered metal mixture consisting essentially of about 0.25% to 15% dispersed, hard particles of crystalline aluminum oxide, 2 to 11% aluminum, 0.3% to 6.5% carbon, and the balance substantially all copper.

sintered powdered of approximately 7. A sintered powdered metal bearing characterized by high Wear and score resistance, high strength and good frictional properties, said bearing being formed from a powdered metal mixture consisting essentially of 1% to 5% aluminum oxide in the form of dispersed finely divided particles, 1% to 13% tin powder, 2% to 11% aluminum powder, and the balance substantially all a metal powder selected from the class consisting of copper and copper base alloys.

8. A sintered powdered metal bearing characterized by high wear and score resistance, high strength and good frictional properties, said heating consisting essentially of 0.25% to 7.5% dispersed hard particles of crystalline A1 0 2% to 11% aluminum, nickel not in excess of 15 0.3% to 6.5% carbon, and the balance substantially all a metal selected from the class consisting of copper and copper base alloys.

9. A sintered powdered metal bearing characterized by 1 high wear and score resistance, high strength and good frictional properties, said bearing being formed from a powdered metal mixture consisting essentially of 1% to 5% pulverized aluminum oxide, 0.3% to 6.5% graphite powder, 2% to 15% nickel powder, 2% to 11% aluminum powder, tin powder not in excess of 18%, 0.3% to "2% die lubricant, and the balance substantially all copper powder.

References Cited in the file of this patent UNITED STATES PATENTS 2,072,070 Fisher Feb. 23, 1937 2,187,086 Koehring Jan. 16, 1940 2,196,875 Sandler et a1. Apr. 9, 1940 2,404,598 Sachse July 23, 1946 2,470,269 Schaeter May 17, 1949' OTHER REFERENCES Goetzel: Treatise on Powder Metallurgy, vol. I, p. 256, New York: Interscience, 1949.

Goetzel: Treatise on Powder Metallurgy, vol. II, (1950), pp. 438-443.

Mathewson, Ed, Modern Uses of Nonferroul M 3818, New York, AIME, 1953, page v28.7-

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,831,243 April 22, 1958 Robert F Thomson It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as eorreeted below.

Column 6, line 11, after "15%" and before the comma insert nickel- 0 Signed and sealed this 8th day of July 19580 (SEAL) Attest:

KARL MINE ROBERT c. WATSON Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 2,831,243 April 22, 1958 Robert Fu Thomson It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said letters Patent should read as corrected below.

Column 6, line 11 after "15%" and before the comma insert niekel a Signed and sealed this 8th day of July 1958 (SEAL) Attest: KARL Ha AXLINE ROBERT C. WATSON Commissioner of Patents Attesting Ofl'icer 

1. A HIGHLY WEAR-RESISTANT SINTERED POWDERED METAL COMPRISING APPROXIMATELY 0.25% TO 15% AL2O3 PARTICLES, 2% TO 15% NICKEL, AND THE BALANCE SUBSTANTIALLY ALL A METAL SELECTED FROM THE CLASS CONSISTING OF COPPER AND COPPER BASE ALLOYS. 